From 1d990882153f36723f9e8717c4401689e64c7a36 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Wed, 24 Sep 2008 20:48:37 +0900 Subject: [PATCH] x86: restore old GART alloc_coherent behavior Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32 for a device having dma_masks > 24bit < 32bits. If GART gets an address that a device can't access to, GART try to map the address to a virtual I/O address that the device can access to. But Andi pointed out, "The GART is somewhere in the 4GB range so you cannot use it to map anything < 4GB. Also GART is pretty small." http://lkml.org/lkml/2008/9/12/43 That is, it's possible that GART doesn't have virtual I/O address space that a device can access to. The above behavior doesn't work for a device having dma_masks > 24bit < 32bits. This patch restores old GART alloc_coherent behavior (before the alloc_coherent rewrite). Signed-off-by: FUJITA Tomonori Signed-off-by: Ingo Molnar --- arch/x86/kernel/pci-gart_64.c | 43 ++++++++++++++++------------------- 1 file changed, 20 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c index 7e08e466b8a..25c94fb96d7 100644 --- a/arch/x86/kernel/pci-gart_64.c +++ b/arch/x86/kernel/pci-gart_64.c @@ -487,31 +487,28 @@ static void * gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr, gfp_t flag) { - void *vaddr; dma_addr_t paddr; unsigned long align_mask; - u64 dma_mask = dma_alloc_coherent_mask(dev, flag); - - vaddr = (void *)__get_free_pages(flag | __GFP_ZERO, get_order(size)); - if (!vaddr) - return NULL; - - paddr = virt_to_phys(vaddr); - if (is_buffer_dma_capable(dma_mask, paddr, size)) { - *dma_addr = paddr; - return vaddr; - } - - align_mask = (1UL << get_order(size)) - 1; - - *dma_addr = dma_map_area(dev, paddr, size, DMA_BIDIRECTIONAL, - align_mask); - flush_gart(); - - if (*dma_addr != bad_dma_address) - return vaddr; - - free_pages((unsigned long)vaddr, get_order(size)); + struct page *page; + + if (force_iommu && !(flag & GFP_DMA)) { + flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32); + page = alloc_pages(flag | __GFP_ZERO, get_order(size)); + if (!page) + return NULL; + + align_mask = (1UL << get_order(size)) - 1; + paddr = dma_map_area(dev, page_to_phys(page), size, + DMA_BIDIRECTIONAL, align_mask); + + flush_gart(); + if (paddr != bad_dma_address) { + *dma_addr = paddr; + return page_address(page); + } + __free_pages(page, get_order(size)); + } else + return dma_generic_alloc_coherent(dev, size, dma_addr, flag); return NULL; } -- 2.41.1